1. Field of the Invention
This invention is concerned with the production of heavy oil from shallow underground deposits of tar sands.
2 Description of the Prior Art
There are vast subterranean deposits of tar sands that are not susceptible to mining. For example, the Athabasca tar sands in Alberta Province, Canada, have been estimated to contain 860 billion bbls. with only 26 billion bbls. recoverable by current technology. Since the heavy oil in tar sands is highly viscous at ambient formation temperatures, it is not recoverable by ordinary production methods. Resort must be had to techniques to make the heavy oil more readily flowable, such as a suitable solvent or heat, or a combination thereof.